The Society for the Psychological Study of Social Issues

Sound Science, Sound Policy

The Trigger That Pulls the Finger

Guns aren’t simply a ready instrument of violence, but can incite it as well.

Posted Nov 19, 2015

By Brad Bushman

We know very little about Chris Harper Mercer, the man who reportedly killed nine people and injured a dozen on October 1, 2015 at an Oregon community college. We do know that he possessed at least 13 guns: the six found on the scene and seven more at his home. We also know that he had a record of mental illness.

Public domain
Chris Harper Mercer
Source: Public domain

Sadly, as President Obama observed, what has followed the Oregon killings is a by now depressing and familiar routine, a debate about the merits and demerits of gun control that is destined to go nowhere. What is conspicuously absent from these debates, however, is a fact that social psychologists have known for decades, but which hasn’t much penetrated public consciousness: Guns aren’t simply a ready instrument of violence, but can incite it as well. The finger pulls the trigger, but the trigger may also be pulling at the finger.

In 1967, Leonard Berkowitz and Anthony LePage conducted a study to determine whether the mere presence of a weapon could increase aggression. Angered participants were seated at a table that had a shotgun and a revolver on it—or badminton racquets and shuttlecocks in the control condition. The items on the table were described as part of another experiment that the researcher had supposedly forgotten to put away. The participant was supposed to decide what level of electric shock to deliver to an accomplice of the experimenter, which was the aggression measure. The experimenter told participants to ignore the items, but apparently they could not. Participants who saw the guns were more aggressive (i.e., gave more intense shocks to the accomplice) than were participants who saw the sports items.

More than 50 other studies have replicated this effect, which has been dubbed the weapons effect. The effect occurs for angry and non-angry individuals, both inside and outside the laboratory. In one field experiment, for example, an accomplice driving a pickup truck remained stalled at a traffic light for 12 seconds. The truck contained either a military rifle in a gun rack mounted to the rear window or no rifle. The results showed that motorists honked more quickly and more frequently (the aggression measures) if the accomplice was driving a truck with a gun visible in the rear window than if there was no gun in the window. If you think about it, you would have to be foolish to honk your horn at a driver with a military rifle in his truck! But people were not thinking—they just automatically honked their horns after seeing the gun. Research also shows that drivers with guns in their vehicles drive more aggressively, even when numerous other factors are controlled (e.g., sex, age, urbanization, census region, driving frequency). The weapons effect has also been observed using toy guns in studies involving children.

American society is saturated with guns. You can even make a gun with a 3-dimensional printer that can fire bullets. Children who live in homes without guns may still be frequently exposed to guns in the mass media. A recent analysis of top-selling films found that the depiction of guns in violent scenes in PG-13–rated films (for viewers 13+) that target youths has increased from the level of G-rated and PG-rated films in 1985, when the rating was introduced, to exceed the level of R-rated films (for viewers 17+) by 2012. Acts of gun violence in PG-13 movies has more than tripled since 1985. By including guns in violent scenes, film producers may be inadvertently increasing aggression in youths via a weapons effect.

In Florida, a man with the Twitter name I’ll call @KissMiGuns decided to show off his 115 guns on the photo-sharing website Instagram. In the months following the Newtown shooting, his followers increased from 8500 to more than 40 000. In a news story about @KissMiGuns I was (accurately) quoted as saying, “the mere presence of weapons can increase aggression.” I received dozens of openly hostile comments from gun owners about this news story, via anonymous comments, e-mails, telephone calls, and letters. It is ironic that gun owners claim that the mere presence of a gun does not increase aggression, yet they have made some of the most aggressive comments I have ever received about my research, providing indirect evidence for the weapons effect. Such hostile comments may even prevent some researchers from talking to the press (and therefore educating the public) about the weapons effect. Fortunately, we have not yet let this vocal minority dominate public discussion (although they do dominate public policy).

Brad J. Bushman is professor of communication and psychology at The Ohio State University. 

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